OBJECTIVETo explore the possibility of pulsed Nd:YAG laser-aided debonding for removing orthodontic metal brackets and to compare the method with the conventional mechanical debonding method.

METHODSFifty healthy premolars extracted for orthodontic purpose were randomly divided into five groups (10 teeth in each group). There were four experimental groups and one control group. Every tooth was bonded with bracket. Laser was used to irradiate the teeth in experimental groups with different electric currents (13.0, 13.5, 14.0, 14.5 A). During the irradiation, the brackets received 4.9 N of force until the brackets off. The time needed for debonding and the temperature change of the pulp cavity were recorded. The teeth in control group were debonded using mechanical method. The adhesive remnant index (ARI) was calculated using stereomicroscope and imagetool software. All samples were examined with a scanning electron microscope.

RESULTSThe time taken between the four groups were (67.70 ± 7.18), (35.90 ± 4.28), (24.90 ± 3.76), (6.90 ± 2.33) s, highly statistical difference was found in the time needed for debonding (P < 0.01). The temperature in the pulp cavity among the four groups were (20.97 ± 3.10), (12.75 ± 3.14), (8.99 ± 2.47), (2.91 ± 1.88)°C, and statistical differences were found in temperature change of the pulp cavity (P < 0.05). ARI of three experimental groups and the control group were (8.55 ± 5.02)%, (15.42 ± 7.37)%, (5.55 ± 3.79)%, (13.72 ± 6.69)%, and (74.36 ± 29.44)%. The enamel surface of the control group was coarse with deep scratchs. The enamel surface was smooth and clean in the experimental groups.

CONCLUSIONSPulsed Nd:YAG laser-aided debonding for removing metal brackets was feasible. Laser-aided debonding was better than conventional mechanical debonding method. The method reduced the damage to the enamel surface.

Dental Debonding ; methods ; Dental Enamel ; Humans ; Lasers, Solid-State ; Orthodontic Brackets

OBJECTIVETo investigate the vertical bone height and the bone density of the palate for implants placement using cone beam CT(CBCT) and to provide references to the safe and stable placement of palatal implants.

METHODSThree-dimensional reformatting images were reconstructed with the selected CBCT scanning data of 34 patients aged 18 to 35 yeras, by means of EZ implant software. The vertical bone height was measured at 20 interesting sites of palate. Bone density was measured at 10 sites that could support 3.0 mm long implants. The data of the vertical bone height and bone density were analyzed by K-means cluster analysis.

RESULTSAccording to the cluster analysis results, the 10 sites were classified into 3 clusters. There were statistical differences among these three clusters in bone height and bone density (P < 0.05). The LSD result showed that the greatest mean value of vertical bone height was obtained in cluster 2, followed by cluster 1 and cluster 3; the highest bone density was founded in cluster 3, followed by cluster 1 and cluster 2.

CONCLUSIONSEvaluation of the sites for palatal implant placement with cone beam CT would be helpful in safe and stable implantation.

Adolescent ; Adult ; Bone Density ; Cone-Beam Computed Tomography ; Dental Implantation, Endosseous ; Female ; Humans ; Male ; Palate ; diagnostic imaging ; Software ; Young Adult

AIMThe purpose of this study was to conduct quantitative research on bone height and bone mineral density of palatal implant sites for implantation, and to provide reference sites for safe and stable palatal implants.

METHODOLOGYThree-dimensional reformatting images were reconstructed by cone beam computed tomography (CBCT) in 34 patients, aged 18 to 35 years, using EZ Implant software. Bone height was measured at 20 sites of interest on the palate. Bone mineral density was measured at the 10 sites with the highest implantation rate, classified using K-mean cluster analysis based on bone height and bone mineral density.

RESULTSAccording to the cluster analysis, 10 sites were classified into three clusters. Significant differences in bone height and bone mineral density were detected between these three clusters (P<0.05). The greatest bone height was obtained in cluster 2, followed by cluster 1 and cluster 3. The highest bone mineral density was found in cluster 3, followed by cluster 1 and cluster 2.

CONCLUSIONCBCT plays an important role in pre-surgical treatment planning. CBCT is helpful in identifying safe and stable implantation sites for palatal anchorage.

Adolescent ; Adult ; Bone Density ; Cluster Analysis ; Cone-Beam Computed Tomography ; Dental Implants ; Female ; Humans ; Male ; Orthodontic Anchorage Procedures ; instrumentation ; Palate ; anatomy & histology ; diagnostic imaging ; Young Adult

OBJECTIVEUsing chitosan (CS)/beta-tricalcium phosphate (TCP)/recombinant human bone morphogenetic protein (rhBMP)-2 for the reconstruction of rabbits' mandible defect, to prove the feasibility of CS/beta-TCP as an injectable bone tissue engineering scaffold material.

METHODSTwenty-four New Zealand white rabbits were randomized into 4 groups on average: Experimental group 1 embedding CS/beta-TCP/rhBMP-2, experimental group 2 embedding CS/ beta-TCP, control group 1 embedding autograft bone group, control group 2 embedding nothing. At 2, 4 and 8 weeks after surgery, all rabbits were executed group by group. The new bone growth situations were observed with hematoxylin-eosin staining and immunofluorescence microscopy, the bone mineral density was detected by bone sonometers.

RESULTSAfter 2, 4, 8 weeks, there was significant difference among the areas of bone regeneration of all groups. The effect of experimental group 1 was better than experimental group 2. There was significant difference at different times, the areas of bone regeneration was gradually increased with time. The area of stained yellow in experimental group 1 was larger, the area of stained red was smaller. The quantities of bone density in experimental group 1 at every time after surgery were significantly higher than experimental group 1 and control group 2, but had no statistical significance with control group 1.

CONCLUSIONCS/beta-TCP/rhBMP-2 has good biocompatibility, degradability and the capacity of guided and inducing osteogenesis. CS/beta-TCP as a good injection of carrier could become a promising carrier for rhBMP-2 and potential new degradable biological material for repairing bone defect in clinical application.

Animals ; Bone Morphogenetic Protein 2 ; Bone Morphogenetic Proteins ; Bone Regeneration ; Bone Transplantation ; Bone and Bones ; Calcium Phosphates ; Chitosan ; Humans ; Osteogenesis ; Rabbits ; Recombinant Proteins ; Tissue Engineering ; Tissue Scaffolds ; Transforming Growth Factor beta

AIM:To investigate the effects of titanium dioxide(TiO2)nanotube arrays on the early adhesion behavior of Porphyromonas gingivalis(Pg),Tannerella forsythia(Tf)and Actinobacillus actinomycetemcomitans(Aa)be-fore and after loaded with minocycline hydrochloride(MN).METHODS: TiO2nanotube arrays were prepared by ano-dization and loaded with MN.Titanium slices were divided into 3 groups according to different treatment methods: pure polishing titanium(Ti)group,TiO2nanotube titanium(TiO2)group, and MN(120 μg)TiO2nanotube titanium(MN TiO2)group.The antibacterial properties of the titanium tablets were evaluated by the bacteriostasis test.RESULTS:The Ti had no antibacterial activity.The antibacterial activity of TiO 2to Aa,Pg and Tf was poor,with only about 20%of anti-bacterial rate after 4 h.After loaded with MN,its antibacterial activity was enhanced,and the antibacterial rate was up to 77%after 4 h.CONCLUSION: No antibacterial activity in the Ti group was observed.If TiO2nanotube arrays were formed on the surface and MN was loaded,the antibacterial activity on periodontal pathogens was stronger.

Abstract：Objective To optimize the production process of inactivated vaccine of Aeromonas veronii（AV）CA07 strain. Methods The fermentation culture process of AV CA07 strain liquid was determined through the optimization of the culture time（2～16 h），medium（optimized fermentation medium，LB medium and NB medium）and fermentation conditions（in⁃ oculation amount of 1%，5%，10% and 15%；ventilation rate of 2，4，6 and 8 L／min and fermentation time of 6，8，10 and 12 h）. The optimal inactivation process was determined through the comparison of the final concentration of formalde⁃ hyde solution（0. 10%，0. 20%，0. 30% and 0. 40%），inactivation temperature（28 and 37 ℃）and inactivation time（24， 48 and 72 h）. The large⁃scale production process of inactivated vaccine of AV CA07 strain in 500 L fermentor was estab⁃ lished and the prepared vaccines were tested for safety and immunogenicity. Results The optimal inoculation amount of AV CA07 strain was 5%，ventilation rate was 4 L／min and culture time was 10 ~ 12 h. The optimal inactivation condition was adding formaldehyde solution with final concentration of 0. 30% incubating at 37 ℃ for 24 h. The number of viable bacteria in the fermentation broth of AV CA07 strain prepared in 500 L fermentor was more than 8 × 109 CFU／mL. All crucian carps immunized with the inactivated vaccine by abdomen survived. After challenge，the relative immune protection rate was more than 90%. Conclusion AV CA07 strain inactivated vaccine prepared by optimized production process showed good safety and immunogenicity.

Objective: To investigate the synergistic effect and mechanism of the combined application of recombinant human bone morphogenetic protein-2 (rhBMP-2) and basic fibroblast growth factor (bFGF). Methods: 24 KM male mice were randomly divided into 6 groups with 4 mice in each group, namely, Group A (control group), Group B (only treated with collagen), Group C (treated with 2 ng bFGF+collagen), Group D (treated with 4 μ g rhBMP-2+collagen), Group E (treated with 4 μ g rhBMP-2+2 ng bFGF+collagen) and Group F (treated with 4 μ g rhBMP-2+4 ng bFGF+collagen). The composites were implanted into the intermuscular septum of hind legs mice; whereas in control group, intermuscular septum of mice was separated and no implantation was performed. General observation, detection of concentration of calcium content, micro computed tomography (Micro-CT), three-dimensional reconstruction scan, measurement of bone mineral density (BMD), bone volume fraction (BVF) and trabecular thickness (Tb.Th), as well as histological observation with HE staining and ALP and CD34 immumohistochemical staining were performed. Results: Ectopic osteogenesis was found in Groups D, E and F mice. The difference in concentration of calcium contents was statistically significant between Groups D and E (. P<0.05), but insignificant between Groups E and F (. P>0.05). Micro-CT and three-dimensional reconstruction revealed continuous newborn bone substance in external surface of ectopic bone formation, and the center of bone formation did not show obvious substantial filling by bone substance. The differences in BMD, BVF and Tb.Th were statistically significant between Groups D and E or F (. P<0.01 or <0.05). HE staining showed that in Groups D, E and F, newborn bone substance was mainly located at the edge of ectopic bone formation, and the bone formation in Groups E and F was better than that in Group D. ALP and CD34 immumohistochemical staining revealed the positive expression mainly at the edge of ectopic bone formation, and area of positive expression in Groups E and F was larger than that in Groups D. Conclusions: rhBMP-2 possesses the capacity to induce ectopic osteogenesis independently, but bFGF does not have this ability; the combined application of rhBMP-2 and bFGF can enhance the synergetic effect on inducing ectopic osteogenesis.